| 摘要 |
PROBLEM TO BE SOLVED: To obtain an objective lens allowed to be used for a microscope, capable of effectively correcting various aberrations by using a glass material with excellent transmissivity in a near ultraviolet area and having usability for both for of fluorescent observation and bright visual field observation and high aperture value. SOLUTION: The objective lens is constituted of a front lens group Lf provided with a junction meniscus lens or meniscus single lens turning its concave face to the object side, having positive refractive power and arranged on the object side and a rear side lens group Lr arranged behind the lens group Lf. In this case, the refractive index nF and Abbe numberνF of a glass material of a meniscus lens (a negative lens 11 and a positive lens 12) arranged on the most object side of the front lens group Lf and the refractive index nR and Abbe numberνR of a glass material of positive lenses 17, 18 of the rear side lens group Lr satisfy the following inequalities. Namely nF<=1.50 andν>65 (1) and nR<=1.65 and 35<νR<50 (2).
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